Conventionally, in light emitting devices using a light emitting element such as LED (light emitting diode) chip or LD (laser diode) chip, some of the devices have been manufactured in accordance with the following steps: Namely, a first lead of a lead frame and a first electrode (n electrode) of the light emitting element, and a second lead of the lead frame and a second electrode (p electrode) of the light emitting element are electrically connected to each other, respectively. Then, after sealing surroundings of the light emitting element with a transparent resin, the first lead and the second lead are cut off from the lead frame.
Also, at this time, either of the first lead and the second lead of the lead frame, in some cases, is formed into a cup shape having an inner space of, e.g., conic pyramid shape, elliptic pyramid shape, or concave mirror shape. Then, the light emitting element is implemented on bottom-surface portion of this cup-shape-formed portion (which, hereinafter, will be referred to as “cup portion”). On account of this configuration, light emitted from side surface of the light emitting element in a direction along the implementation surface can be reflected on concave-portion surface of the cup portion. This allows the light to be gathered and directed in advance in a predetermined direction, thereby allowing an enhancement in light-emission efficiency.
Also, in the light emitting element, semiconductor layers engaged in performing the light emission, such as, e.g., n-type semiconductor layer, light emitting layer, and p-type semiconductor layer, are multilayered via a buffer layer on one principal surface of the substrate.
Also, in the light emitting element, when roughly classified, there exist two ways to provide the first electrode and the second electrode. One is a method of providing the first electrode (n electrode) on rear surface of the principal surface of the substrate on which the semiconductor layers engaged in performing the light emission are multilayered, and providing the second electrode (p electrode) on the p-type semiconductor layer. The other is a method of exposing the n-type semiconductor layer by eliminating part of the p-type semiconductor layer and the light emitting layer multilayered on the substrate, and providing the first electrode on the n-type semiconductor layer exposed, and providing the second electrode on the p-type semiconductor layer.
Also, in recent years, there has existed a tendency that the amount of heat generated by the light emitting layer of the light emitting element increases because of high-luminance implementation of the light emitting element. On account of this, when implementing the light emitting element on the cup portion, the second electrode (p electrode) tends to be implemented in a manner faced to the bottom surface of the cup portion, so that the distance between the light emitting layer and the cup portion will become more proximate. At this time, if the first electrode (n electrode) is provided on the rear surface of the principal surface of the substrate on which the semiconductor layers engaged in performing the light emission are multilayered, the first electrode and the first lead are electrically connected via a bonding wire.
Also, if the first electrode is provided on the n-type semiconductor layer, e.g., a metallic layer with an intervention of an insulating layer is provided beforehand in a partial area of the bottom surface of the cup portion. Then, the first electrode and the metallic layer are electrically connected. Moreover, the metallic layer and the first lead are electrically connected via the bonding wire, thereby connecting the first electrode and the first lead electrically (Refer to, e.g., Patent Document 1 and Patent Document 2.).
Also, in recent years, in the light emitting element, a light-through substrate such as, e.g., sapphire has tended to be used as the substrate. As a result, not only the light emitted from the side surface of the light emitting element, but light emitted from the light emitting layer onto the substrate side can also be emitted to the outside of the light emitting element. On account of this, when the second electrode (p electrode) is implemented in a manner faced to the bottom surface of the cup portion, the light emitted from the substrate side and the light reflected on the concave-portion surface of the cup portion are capable of being gathered and directed, thereby being able to be outputted to the outside of the light emitting device. This enhances the light-emission efficiency further.
However, when the first electrode of the light emitting element and the first lead are electrically connected via the bonding wire, the light emitted from the side surface of the light emitting element and the light emitted in such a manner that it passes through the light-through substrate are partially intercepted by the bonding wire. On account of this, there has existed the following problem: Namely, a shadow or light unevenness reflecting shape of the bonding wire occurs in the light outputted from the light emitting device. This lowers the light-emission efficiency. At this time, it is possible to reduce the problem of the light unevenness and the lowering in the light-emission efficiency by using an extremely thin bonding wire. However, when the extremely thin bonding wire is used, there exists the following problem: Namely, electrical resistance of the bonding wire results in a lowering in current capacity, thereby making it difficult to obtain the high luminance.    Patent Document 1: JP-A-6-314822    Patent Document 2: JP-A-11-251645